535d Engine RPM increasing and decreasing

[Monster26]

Drove my father inlaws 535d Sport (yr 2005) in to work today and noticed that the Engine increases and decreases in RPM with no manual input as your driving along...

If your driving along at 40 on the flat in Drive with constant pressure on throttle the you can see the Rev counter rise and fall and you can feel the car pulling or slowing inline with the rev counter, the movement is only slight but you know somethings amiss (sensitive Bum....). I'm only talking 100-200 rpm rise and fall but it's noticable.

This also happends at 70 on the motorway, you can see the rev counter moving alittle more too. Maybe speed related.

Can anyone help with this or is it straight to the Dealer? Any help will be greatly appreciated.

Thanks,
Mark

[Not Ideal]

Hmmm throttle sensor..??

[Monster26]

Been thinking...

Do the computers that read sensors only read fault codes when a fault code shows up on a dash?

As the car spends most of it's life in slow Bristol Traffic would a good blat on the motorway with a warm engine be a good idea? Could be a clogged sensor?

How do thes cars idle? could it be an idle control valve problem causing the hunting effect but at a higher rpm?

How would I test the trottle sensors? (garage I suppose)

cheers,
M

[juliann]

Mines done this for a while and Dealer couldn't diagnose. ZF specialist suggested it was the autobox.

Will be interested to see if you come to a different conclusion.

[Monster26]

juliann said:

Mines done this for a while and Dealer couldn't diagnose. ZF specialist suggested it was the autobox.

Will be interested to see if you come to a different conclusion.

Crumbs... thats gonna get expensive. Have contacted a garage friend with the Computer thingy and will see if a sensor is on the way out. Whos ZF?
thanks, M

Edited by Monster26 on Wednesday 26th August 16:10

[phumy]

ZF gearboxes are probably one of the biggest and best manufacturer of gearboxes fitted to powerful cars, can be found here: http://www.zf-group.co.uk/

If you go to the dealer they wont fix it but they will rape you for a new one at around 4k a piece, if you go to ZF direct they will do you either a service, (the dealer wonr even offer it) or supply a new box for around 1.5k, a damn sight cheaper than the main dealer.

[Monster26]

Thanks.

I do think it's the gearbox. On the way home it wouldn't select the correct gear going up a steep hill. Doing 70 it did the same as in the morning.

Also on the motorway it got confused at 20mph (yes 20...!) hickuping as if it was manual with a learner driving.

Time to hand it back and help get it sorted.

[E21_Ross]

shocking on a 4 year old car!!! will be interesting to see what happens! good luck.

[Monster26]

Took the car back last night, and it's going back into the dealership for a service and diagnosis, then off to an independant for the work depending whats found. I'll report back.
Any more opinions welcome.

[phelix]

How many miles? I think someone else here had similar problems - turned out to be the torque convertor.

[stevegarry0]

i had very same problem with my e60 530d.. took it to main dealer and it was the air flow sensor £250.... its fine now and pulls like a train..

[fme]

Hi, new here. my recently bought 525i auto (02plate) had gearbox light come on and the car would not drive unless i put my foot harder on the accelerator. A friend said it could be torque convertor. So I took it local BMW indepnedent, put it on computer came up with stall monitor; he cleared this and the car drives perfeclty. Best thing is to get the diagnostics done.

[dxb335d]

stevegarry0 said:

i had very same problem with my e60 530d.. took it to main dealer and it was the air flow sensor £250.... its fine now and pulls like a train..

How many miles mate?